Balance assembly for rotary turbine component and method for installing and/or adjusting balance weight

ABSTRACT

A balance assembly for turbine rotating components, such as turbine rotors, as well as method for installing and/or adjusting at least one balance weight in the balance assembly and turbine section having this balance assembly and a radially extending access pathway for accessing this balance assembly. The balance assembly comprises; (a) a balance weight retention member having a circumferential periphery and a slot formed therein along at least a portion thereof, the slot having: ( 1 ) a bottom surface; ( 2 ) an opening; and ( 3 ) a pair of spaced apart and opposed side walls connecting the bottom surface and the opening, the side walls sloping inwardly between the bottom surface and the opening to define a balance weight engaging section; (b) at least one balance weight configured and sized to be insertable through the opening of the slot and to be positionable for movement within the slot and having a pair of spaced apart generally inwardly sloping shoulder surfaces capable of engaging the side walls of the slot at the balance weight engaging section; and (c) a balance weight securing member associated with the at least one balance weight that can be actuated to: (1) move the at least one balance weight away from the bottom surface so that the shoulder surfaces engage the side walls at the balance weight engaging section such that the at least one balance weight is in a secured position within the slot; or (2) move the at least one balance weight towards the bottom surface so that the shoulder surfaces do not engage the side walls at the balance weight engaging section such that the at least one balance weight is in a unsecured position within the slot.

BACKGROUND OF THE INVENTION

This invention relates generally to a balance assembly for a rotaryturbine component such as a turbine rotor. This invention also relatesto a method for installing one or more balance weights in this balanceassembly, as well as adjusting the balance weight(s) after installation.This invention further relates to a turbine section having this balanceassembly and a radially extending access pathway for accessing thisbalance assembly.

In the production of turbine engines, the balancing of the rotaryturbine components, such as turbine rotors, can be an essential andimportant step. The turbine rotors are typically balanced initiallyprior to the actual assembly of the engine. This balancing can beachieved in variety of ways, for example, by the attachment of specialweights designed to fit on bolts or within grooves of the rotor orassociated components, or by grinding material from specified sectionson the rotor. See U.S. Pat. No. 4,220,055 (Dubois et al), issued Sep. 2,1980 (balance weight having beak engaging groove of collar and securedto rotor by rivet); U.S. Pat. No. 4,803,893 (Bachinski), issued Feb. 14,1989 (balance weights located in groove of cover plate for rotorassembly); commonly assigned U.S. Pat. No. 5,011,374 (Miller), issuedApr. 30, 1991 (balance clips attached to shroud of rotor); commonlyassigned U.S. Pat. No. 5,018,943 (Corsmeier et al), issued May 28, 1991(balance weight mounted in dovetail slots formed in circumference ofrotor disk and bottom of dovetail root of rotor blades inserted withindovetail slots). Due to subsequent operations in assembling the engine,there is often a need for further adjustment or balancing of the rotarycomponents after this engine is completed. This is commonly referred toas “trim balancing.” During subsequent operation of the turbine engine,adjustment or rebalancing of the rotary components can also benecessary.

A problem with certain balancing systems for rotors is that trimbalancing or rebalancing of the rotors can require partial or completedisassembly of the engine in order to access the balance weights. Forexample, one prior balancing system uses balance weights that areinserted into a circular or circumferential groove or slot typicallyformed in the face or circumference of the disk, wheel and/or spacer ofthe rotor, with the weights then being moved or adjusted within thegroove or slot to achieve the desired degree of balancing. See commonlyassigned U.S. Pat. No. 3,736,811 (Neary), issued Jun. 5, 1973 (balanceweight inserted in balance groove formed in face of turbine wheel andlocked in place anywhere along balance groove by screw adjustment); U.S.Pat. No. 4,842,485 (Barber), issued Jun. 27, 1989 (circular grooveformed in at least one face of turbine to receive weight assemblycomprising arcuate body member with bore and slots in side walls toallow expansion by expander screw); commonly assigned U.S. Pat. No.6,481,969 (Berry et al), issued Nov. 19, 2002 (dovetail-shaped groovesformed in axial faces and circumferential rims of wheels and spacers ofrotor body and complementary-shaped balance weights inserted throughentry apertures in grooves and circumferentially aligned into adjustedpositions). After the balance weights are secured in place in the grooveor slot, and the engine is completely assembled, these balance weightsare typically intended to be fixed in position and not moved again toreadjust or trim the balance of the rotary component. As a result, thesebalance weights are usually inaccessible without at least partialdisassembly of the engine. Certain of these balance weight systems alsorequire specially formed access ports or openings in the groove or slotso that the balance weights can be inserted. See FIGS. 1 and 2 of U.S.Pat. No. 3,736,811 (prior art) and FIG. 5 of U.S. Pat. No. 6,481,969.Such access ports or openings can cause a lack of symmetry in weightdistribution of the balance assembly, as well as creating potentialweaknesses in the balance assembly with regard to the concentration ofstresses.

Balance systems for rotary components of turbine engines have also beendeveloped that allow for remote access to areas of the engine where thebalance weights are already installed, or where the balance weights canbe inserted, for trim balancing or rebalancing without disassembly ofthe engine. Some of these balance systems can require that the balanceweight be inserted at a specific location, thus making finer balanceadjustments more difficult to achieve. See U.S. Pat. No. 2,964,972(Lindsey et al), issued Dec. 20, 1960 (balance assembly for rotorcomprising annular member provided with plurality of circumferentiallyspaced thread holes that can be accessed through pathway to receivebalance weights delivered by special tool); U.S. Pat. No. 5,545,010(Cederwall et al), issued Aug. 13, 1996 (trim balancing of turbine rotorby adding or removing balance weights or plugs through compressor airflow path and pair of holes). Some of these remote access balancingsystems allow for insertion of the balance weight at various positionsin a groove or slot formed in the rotor assembly. See U.S. Pat. No.4,064,762 (Wilkner), issued Dec. 27, 1977 (tool for inserting balanceweight into dovetail groove in rotor disk); commonly assigned U.S. Pat.No. 6,279,420 (Knorowski et al), issued Aug. 28, 2001 (balance weightgroove formed in rotor, a balance weight having a threaded opening forreceiving a screw and a threaded tool for inserting the balance weightin the groove, rotating the screw to lock the balance weight in thegroove, and a staking tool that is inserted to stake the balance weightand rotor, as well as the screw and balance weight). However, after thebalance weight is inserted into the groove, it is, again, typicallyintended to be fixed in place and not moved again to readjust or trimthe balance of the rotary component.

Accordingly, it would be desirable to provide a balance assembly forrotary turbine components, such as turbine rotors, that can be used totrim balance or rebalance the rotor while the turbine engine remainscompletely or substantially completely assembled. It would also bedesirable to provide a balance assembly for turbine rotors where thebalance weights can be relatively easily located or moved to differentpositions to allow for relatively fine adjustments of the balancing ofthe rotor. It would also be desirable to be able to install the balanceweights without the need of specially formed access ports or openings inthe balance assembly. It would be further desirable to provide a balanceassembly for turbine rotors where the balance weights can be relativelyeasily readjusted after initial installation for subsequent trimbalancing and rebalancing of the rotor.

BRIEF DESCRIPTION OF THE INVENTION

An embodiment of this invention relates to a balance assembly for rotaryturbine components, such as turbine rotors. This assembly comprises:

-   -   a. a generally annular balance weight retention member having a        circumferential periphery and a slot formed therein along at        least a portion thereof, the slot having:        -   (1) a bottom surface;        -   (2) an opening spaced from the bottom surface; and        -   (3) a pair of spaced apart and opposed side walls connecting            the bottom surface and the opening, the side walls sloping            inwardly between the bottom surface and the opening to            define a balance weight engaging section;    -   b. at least one balance weight being configured and sized to be        insertable through the opening of the slot and to be        positionable for movement within the slot and having a pair of        spaced apart generally inwardly sloping shoulder surfaces        capable of engaging the side walls of the slot at the balance        weight engaging section; and    -   c. a balance weight securing member associated with the at least        one balance weight that can be actuated to:        -   (1) move the at least one balance weight away from the            bottom surface so that the shoulder surfaces engage the side            walls at the balance weight engaging section such that the            at least one balance weight is in a secured position within            the slot; or        -   (2) move the at least one balance weight towards the bottom            surface so that the shoulder surfaces do not engage the side            walls at the balance weight engaging section such that the            at least one balance weight is in a unsecured position            within the slot.

Another embodiment of this invention relates to a method for installingat least one balance weight in this balance assembly. This methodcomprises the steps of:

-   -   11. inserting the at least one balance weight through the        opening of the slot of the balance weight retention member so        that the at least one balance weight is in a first inserted        position within the slot;    -   2. adjusting the at least one balance weight from the first        inserted position to a second securing member associating        position within the slot so that the at least one balance weight        is capable of being associated with the balance weight securing        member; and    -   3. associating the balance weight securing member with the at        least one balance weight while in the second position.

Another embodiment of this invention relates to a section of a turbineengine having this balance assembly and a radially extending accesspathway for accessing this balance assembly.

The balance assembly and method of this invention, as well as thesection of the turbine engine having the radially extending accesspathway for accessing this balance assembly, provides a number ofsignificant benefits and advantages in the balancing of rotary turbinecomponents such as turbine rotors. The balance assembly, method andsection of the turbine engine having the radially extending accesspathway for accessing the balance assembly of this invention allows therotary turbine components to be trim balanced or rebalanced while theturbine engine remains completely or substantially completely assembled.The balance assembly, method and section of the turbine engine havingthe radially extending access pathway for accessing the balance assemblyof this invention allows the balance weight(s) to be located or moved todifferent positions in the balance assembly to allow for relatively fineadjustment in the balancing of the rotor. The balance weight(s) andassociated slot of the balance weight retention member are also sizedand configured such that specially formed balance weight access ports oropenings are not required for insertion of the balance weight(s) intothe slot. The balance assembly and section of the turbine engine havingthe radially extending access pathway for accessing this balanceassembly of this invention also allow for relatively easy readjustmentof the balance weight(s) after insertion into the slot for subsequenttrim balancing and rebalancing of the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary cross-section of a section of a turbine engineshowing an embodiment of the balance assembly of this invention with aninstalled balance weight.

FIG. 2 is an enlarged sectional view of the balance assembly of FIG. 1.

FIG. 3 is a view similar to FIG. 2 showing the insertion of a balanceweight in the slot of the balance weight retention member.

FIG. 4 is a view similar to FIG. 3 showing the inserted balance weightmoved, adjusted or rotated from the initial inserted position to asecond position where the balance weight can be associated with thebalance weight securing member.

FIG. 5 is a view similar to FIG. 1 showing an access way in a section ofa turbine engine for accessing the balance assembly, as well as a toolinserted through this access way for unsecuring, moving and/or securingthe balance weight.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, FIG. 1 illustrates a fragmentarycross-section of a representative section of a turbine engine that isindicated generally as 10 in which the balance assembly of thisinvention can be used. Turbine engine section 10 is shown as having aturbine rotor indicated generally as 14. Turbine engine section 10 canbe any section having such a rotor 14, including but not limited to ahigh pressure (HP) compressor section, a low pressure (LP) compressorsection, an HP turbine section, a LP turbine section, an intermediatepower (IP) turbine section, or a power (PW) turbine section. In otherwords, the turbine engine section 10 shown in FIG. 1, and as describedhereafter, should be considered only representative of the use of theembodiment of the balance assembly of this invention.

As shown in FIG. 1, rotor 14 comprises a plurality of circumferentiallyspaced turbine blades, one of which is indicated as 18, that extendradially from a central hub or disk indicated as 22. The root 24 ofblade 18 is positioned between a blade retainer 26 and interstage seal28 that together are secured to disk 22 by a bolt assembly indicatedgenerally as 30. As shown in FIG. 1, turbine engine section 10 alsoincludes a support structure indicated generally as 34 for thestationary portion 38 of a pressure seal. The pressure seal alsoincludes a rotating portion 42 that is secured to a rotating shaft 46 bya bolt assembly indicated generally as 50. Bolt assembly 50 also securesrotating pressure seal portion 42 and shaft 46 to the rearward annularportion 54 of disk 22.

As shown in FIG. 1, an embodiment of the balance assembly of thisinvention indicated generally as 58 is used to balance rotor 14. Thisbalance assembly 58 includes a balance weight retention member indicatedgenerally as 62, at least one balance weight indicated generally as 66and a balance weight securing member in the form of a threaded boltindicated generally as 70. The balance weight retention member 62includes a support portion 74 typically having a concentric rabbetformed therein for securing or attaching member 62 to the concentricouter surface 78 of rearward portion 54 of disk 22. To prevent rotationof balance weight retention member 62 around or about the concentricouter surface 78 of rearward portion 54, support portion 74 can beprovided with a slot (not shown) that receives the head of a spring pin(not shown) that is secured to the rearward portion 54 of disk 22.

As shown more particularly in FIG. 2, balance weight retention member 62also includes a generally annular balance weight retention portion 86.Balance weight retention portion 86 is provided with a slot 90 that isformed along at least a portion of the circumferential periphery 92 ofretention portion 86, and is more typically formed along the entirelength of periphery 92. As shown in FIG. 2, slot 90 typically has agenerally dove-tail shaped cross sectional configuration. Slot 90 has abottom surface indicated as 94, an opening spaced from bottom surface 94indicated generally as 98 at the top of slot 90, and a pair of spacedapart and opposed side walls indicated as 102 and 106 connecting thebottom surface 94 to opening 98.

As shown in FIG. 2, side walls 102, 106 are shaped or configured todefine a generally rectangular-shaped lower section 110 of slot 90 whereside walls 102, 106 extend generally upwardly and perpendicularly fromthe respective ends of bottom surface 94, an intermediate generallytrapezoidal or wedge-shaped section 114 of slot 90 adjacent to lowersection 110 where side walls 102, 106 generally converge or slopeinwardly from the top of lower section 110 to form a constrictionindicated as 118 at the top of intermediate section 114, and an uppergenerally trapezoidal or wedge-shaped section 120 of slot 90 adjacent tointermediate section 114 and generally diverging or sloping outwardlyfrom constriction 118 to opening 98. At least upper and intermediatesections 120 and 114 of slot 90, and also usually lower section 110 ofslot 90, typically have substantially the same cross-sectionalconfiguration and width dimensions along the entire circumferentiallength of slot 90. In particular, the width between the spaced apartpair edges 122 and 124 of opening 98 is typically substantially uniformor essentially the same along the entire length of slot 90, e.g., alongthe entire circumferential periphery 92.

As shown in FIG. 2, balance weight 66 includes a base portion indicatedgenerally as 126 having a generally planar bottom surface 130, a pair ofspaced apart outwardly diverging or sloping generally planar surfaces132 and 136 connected at each end of bottom surface 130, and a pair ofspaced apart upwardly extending generally planar surfaces 140 and 144connected at the respective ends of outwardly sloping surfaces 132, 136.As shown in FIG. 2, balance weight 66 also includes a generallytrapezoidal or wedge-shaped shoulder portion indicated generally as 148adjacent to base portion and having a pair of spaced apart generallyinwardly converging or sloping shoulder surfaces 152 and 156 connectedat the respective ends of upwardly extending surfaces 140 and 144. Asalso shown in FIG. 2, balance weight 66 further includes a generallyrectangular-shaped neck portion indicated generally as 160 adjacent toshoulder portion 148 and having a pair of spaced apart generally planarupwardly extending neck surfaces 164 and 168 connected at the respectiveends to shoulder surfaces 152, 156 and a generally planar top surface172 connected at the respective ends to neck surfaces 164, 168. As shownin FIG. 2, top surface 172 is typically substantially parallel to bottomsurface 130.

As shown in FIG. 2, bolt 70 has a head 176 connected to a threadedgenerally cylindrical shaft 180 having a distal end indicated generallyas 184. As shown in FIG. 2, balance weight 66 has a complementarythreaded portion for receiving threaded shaft 180 in the form of athreaded cylindrical insert 188 positioned within a generallycylindrical bore 192 that extends from the top surface 172 to the bottomsurface 130 of balance weight 66. As shown in FIG. 2, balance weight 66is typically substantially symmetrical about the centerline defined bycylindrical insert 188. As shown in FIG. 2, bolt 70 is also providedwith a locking member in the form of locking pin 196 that is insertedthrough a generally cylindrical bore 200 formed in distal end 184perpendicular to the longitudinal axis of shaft 180. When inserted intobore 200, locking pin 196 prevents bolt 70 from accidentally beingcompletely disconnected from balance weight 66 as bolt 70 is unscrewed.

Balance weight 66 is shown in FIGS. 1 and 2 as being in a securedposition within slot 90 such that balance weight 66 cannot be movedwithin slot 90. This is achieved by turning or screwing bolt 70 intoinsert 188 in the “secure position” direction such that the distal end184 of shaft 180 projects further outwardly away from the bottom surface130 of balance weight 66 and towards bottom surface 94 of slot 90. Asbolt 70 is screwed further into insert 188 so that distal end 180continues to project further outwardly from bottom surface 130, distalend 180 eventually engages bottom surface 94 so that balance weight 66is forced away from bottom surface 94. As a result, shoulder surfaces152, 156 of balance weight 66 are moved towards side walls 102, 106where they slope inwardly at intermediate section 114 of slot 90. Asbalance weight 66 moves further away from bottom surface 94 of slot 90,neck portion 160 will eventually be guided through constriction 118 andinto the upper section 122 of slot 90. Eventually, shoulder surfaces152, 156 will engage respective side walls 102, 106 at intermediate(i.e., “balance weight engaging”) section 114 until bolt 70 can nolonger be screwed into insert 188 of balance weight 66. As this point,balance weight 66 is held in a place in a secured and relativelyimmovable position due to the force of distal end 180 of shaft 174against bottom surface 94 of slot 90 and the frictional engagement ofshoulder portions 152, 156 against respective side walls 102, 106 at theintermediate (i.e., “balance weight engaging”) section 114 of slot 90.As also shown in FIG. 2, when balance weight 66 is in this securedposition, bottom surface 130 of balance weight 66 is typicallysubstantially parallel to bottom surface 94 of slot 90.

In order to install or position balance weight 66 within slot 90, bolt70 is initially not attached or associated with balance weight 66.Instead, as shown in FIG. 3, balance weight 66 is inserted throughopening 98 and upper section 122 of slot 90 without being associatedwith bolt 70. Insertion of balance weight 66 within slot 90 is typicallycarried out before balance weight retention member 62 is secured torearward portion 54 of disk 22. As shown in FIG. 3, balance weight 66 istypically inserted through opening 98 and upper section 122 at a slantedangle, i.e., such that bottom surface 130 of balance weight 66 is notperpendicular to bottom surface 94 of slot 90. Because the width ordimension of balance weight 66 defined by top surface 172 and bottomsurface 130 is less than the width defined by constriction 118, as wellas the width defined by and between outwardly sloping surface 204 (or206) of slot 90 at upper section 122 and inwardly sloping surface 208(or 210) of slot 90 at intermediate section 114, balance weight 66 canbe inserted into slot 90 without the need of specially configured accessports or openings. Indeed, balance weight 66 can typically be insertedthrough opening 98 and upper section 122 of slot 90 at any positionalong the length thereof, e.g. along circumferential periphery 92.

From this first inserted position indicated generally as 212 in FIG. 3,and because of the configuration and size of balance weight 66, as wellas the configuration and size of slot 90 at intermediate and lowersections 114 and 110, balance weight 66 can then be moved, adjusted orrotated to a second position indicated generally as 216 in FIG. 4 withinlower section 110 of slot 90. When in second position 216, balanceweight 66 is fully within and movable in slot 90 (e.g., within lowersection 110) and is also capable of receiving bolt 70. When bolt 70 isscrewed into insert 188 in balance weight 66 such that bore 200 isbeyond bottom surface 130, locking pin 196 can then be inserted intobore 200 to prevent bolt 70 from being accidentally disassociated ordisconnected from balance weight 66 when bolt 70 is unscrewed.

FIG. 5 shows turbine engine section 10 with a portion of the supportingstructure indicated generally as 300 having formed therein respectiveouter and inner access holes 304 and 308 to provide a radially extendingpathway indicated generally as 312 for access to balance assembly 58. Asshown in FIG. 5, a tool indicated generally as 316 is provided with anelongated shaft 320 that is inserted into pathway 312. Attached at thedistal end of shaft 320 is a bolt driver section 324 that is configuredor shaped for insertion into the inner driven section 328 of bolt head176. Typically, bolt drive section 324 and driven section 328 havecomplementary hexagonal, square or other shaped cross-sections. Byrotating or turning shaft 320 in the desired direction, bolt 70 can bescrewed or unscrewed in a direction that will cause balance weight 66 tobe either moved away from bottom surface 94 of slot 90 such that balanceweight 66 is in a secured position, or towards bottom surface 94 suchthat balance weight 66 is in unsecured position. When balance weight 66is in an unsecured position, it can then be moved anywhere along thecircumferential length of slot 90 (e.g., within lower section 110) toany desired balancing position by simply rotating rotor 14 while tool316 is in use. When balance weight 66 has reached the desired position,it can then secured within slot 90 as previously described.

While FIGS. 1-5 show only one balance weight 66, it should be understoodthat typically more than one balance weight 66 is inserted, positionedor present within slot 90. Indeed, typically a pair of balance weights66 are inserted, positioned or present within slot 90. During initiallybalancing of rotor 14, the pair of balance weights 66 are typicallymoved within slot 90 such that they are approximately 180° opposite eachother. As balance assembly 58 requires adjustment to trim balance orrebalance rotor 14, the balance weights 66 can be moved to differentpositions within slot 90 to achieve the desired degree of balancing. Ifthree balance weights 66 are inserted within slot 90, they are typicallymoved initially within slot 90 to provide approximately 120° spacing(i.e., approximately equal spacing) from each other, and so on in likefashion or manner where more than three balance weights are inserted.

After the balance weight(s) 66 are inserted and initially positionedwithin slot 90, the positioning of balance weight(s) 66 within slot 90can be adjusted as needed or desired to balance rotor 14. For example,the positioning of balance weight(s) 66 can be adjusted after theinitial operation of rotor 14 to provide subsequent or further balancingthereof, e.g., trim balancing. Access to balance weight(s) 66 tocarrying out such subsequent or further balancing of rotor 14 istypically achieved by rotating or turning rotor 14 so that eachrespective balance weight 66 whose position needs to be adjusted isaccessible by tool 316 via pathway 312. The position of the accessedbalance weight 66 can then be adjusted with slot 90 as needed.

While specific embodiments of this invention have been described, itwill be apparent to those skilled in the art that various modificationsthereto can be made without departing from the spirit and scope of thisinvention as defined in the appended claims.

1. A balance assembly for a rotary turbine component, which comprises:a. a generally annular balance weight retention member having acircumferential periphery and a slot formed therein along at least aportion thereof, the slot having: (1) a bottom surface; (2) an openingspaced from the bottom surface; and (3) a pair of spaced apart andopposed side walls connecting the bottom surface and the opening, theside walls sloping inwardly between the bottom surface and the openingto define a balance weight engaging section; b. at least one balanceweight being configured and sized to be insertable through the openingof the slot and to be positionable for movement within the slot andhaving a pair of spaced apart generally inwardly sloping shouldersurfaces capable of engaging the side walls of the slot at the balanceweight engaging section; and c. a balance weight securing memberassociated with the at least one balance weight that can be actuated to:(1) move the at least one balance weight away from the bottom surface sothat the shoulder surfaces engage the side walls at the balance weightengaging section such that the at least one balance weight is in asecured position within the slot; or (2) move the at least one balanceweight towards the bottom surface so that the shoulder surfaces do notengage the side walls at the balance weight engaging section such thatthe at least one balance weight is in a unsecured and movable positionwithin the slot.
 2. The assembly of claim 1 wherein the slot has agenerally dovetail-shaped cross-section.
 3. The assembly of claim 2wherein the slot is formed in the balance weight retention member alongthe entire circumferential periphery thereof.
 4. The assembly of claim 3wherein the opening of the slot has a substantially uniform width alongthe entire circumferential periphery.
 5. The assembly of claim 2 whereinthe balance weight engaging section of the slot has a generallytrapezoidal shape.
 6. The assembly of claim 1 wherein there are at leasttwo balance weights.
 7. The assembly of claim 6 wherein there are a pairof balance weights.
 8. The assembly of claim 1 wherein the balanceweight securing member comprises a bolt having a threaded shaft andwherein the at least one balance weight has a threaded portion forreceiving the threaded shaft that extends from the top to the bottom ofthe at least one balance weight.
 9. The assembly of claim 8 wherein thethreaded shaft has a distal end that projects outwardly away from thebottom of the at least one balance weight when the bolt is turned in thesecured position direction and engages the bottom surface of the slot sothat the at least one balance weight is forced away from the bottomsurface of the slot and towards the side walls of the slot at thebalance weight engaging section thereof.
 10. The assembly of claim 10which further comprises a locking member for preventing the bolt frombeing disconnected from the at least one balance weight.
 11. Theassembly of claim 10 wherein the locking member comprises a generallycylindrical bore formed in the distal end of the shaft perpendicular tothe longitudinal axis thereof and a locking pin that is insertable intothe bore.
 12. A balance assembly for a rotary turbine component, whichcomprises: a. a generally annular balance weight retention member havinga circumferential periphery and a slot formed therein along at least aportion thereof, the slot having: (1) a bottom surface; (2) an openingspaced from the bottom surface; and (3) a pair of spaced apart andopposed side walls connecting the bottom surface and the opening, andbeing configured to define: (a) a lower section of the slot wherein theside walls extend generally upwardly from the bottom surface; (b) anintermediate section of the slot adjacent to the lower section andwherein the side walls slope generally inwardly to form a constrictionat the top of the intermediate section; and (c) an upper section of theslot adjacent to the intermediate section and wherein the side wallsslope generally outwardly from the constriction to the opening; b. atleast one balance weight being configured and sized to be insertablethrough the opening and upper section of the slot and to be positionablefor movement within the slot and having: (1) a base portion with a widthsmaller than the width defined by the lower section of the slot so thatthe at least one balance weight is movable within the slot; and (2) ashoulder portion connected to the base portion and having a pair ofspaced apart shoulder surfaces sloping generally inwardly so as to becapable of engaging the side walls at the intermediate section of theslot; and c. a balance weight securing member associated with the atleast one balance weight that can be actuated to: (1) move the at leastone balance weight away from the bottom surface so that the shouldersurfaces engage the side walls at the intermediate section such that theat least one balance weight is in a secured position within the slot; or(2) move the at least one balance weight towards the bottom surface sothat the shoulder surfaces do not engage the side walls at theintermediate section such that the at least one balance weight is in aunsecured and movable position within the slot.
 13. The assembly ofclaim 12 wherein the slot is formed in the balance weight retentionmember along the entire circumferential periphery thereof.
 14. Theassembly of claim 13 wherein the opening of the slot has a substantiallyuniform width along the entire circumferential periphery.
 15. Theassembly of claim 13 wherein the slot has a generally dovetail-shapedcross-section.
 16. The assembly of claim 15 wherein the upper sectionand intermediate section of the slot each have a generally trapezoidalshape and wherein the shoulder portion of the at least one balanceweight has a generally trapezoidal shape.
 17. The assembly of claim 12wherein the balance weight securing member comprises a bolt having athreaded shaft and wherein the at least one balance weight has athreaded portion for receiving the threaded shaft that extends from thetop to the bottom of the at least one balance weight.
 18. The assemblyof claim 17 wherein the threaded shaft has a distal end that projectsoutwardly away from the bottom surface of the at least one balanceweight when the bolt is turned in the secured position direction andengages the bottom surface of the slot so that the at least one balanceweight is forced away from the bottom surface of the slot and towardsthe side walls of the slot at the intermediate section thereof.
 19. Theassembly of claim 10 which further comprises a generally cylindricalbore formed in the distal end of the shaft perpendicular to thelongitudinal axis thereof and a locking pin that is insertable into thebore.
 20. The assembly of claim 12 wherein the at least one balanceweight further comprises a neck section adjacent to the shoulder sectionthat is sized and configured to be capable of fitting within theconstriction in the slot.
 21. A method for installing at least onebalance weight in a balance assembly for a rotary turbine component, thebalance assembly comprising: (a) a generally annular balance weightretention member having a circumferential periphery and a slot formedtherein along at least a portion thereof, the slot having a bottomsurface, an opening spaced from the bottom surface and a pair of spacedapart and opposed side walls connecting the bottom surface and theopening, the side walls sloping inwardly between the bottom surface andthe opening to define a balance weight engaging section; (b) the atleast one balance weight being configured and sized to be insertablethrough the opening of the slot and to be positionable for movementwithin the slot and having a pair of spaced apart generally inwardlysloping shoulder surfaces capable of engaging the side walls of the slotat the balance weight engaging section, the method comprising the stepsof:
 1. inserting the at least one balance weight through the opening ofthe slot of the retention member so that the at least one balance weightis in an inserted position within the slot;
 2. adjusting the at leastone balance weight from the inserted position to a balance weightsecuring member associating position within the slot so that the atleast one balance weight is capable of being associated with the balanceweight securing member; and
 3. associating a balance weight securingmember with the at least one balance weight while in the balance weightsecuring member associating position, the balance weight securing memberbeing capable of being actuated to: (a) move the at least one balanceweight away from the bottom surface so that the shoulder surfaces engagethe side walls at the balance weight engaging section such that the atleast one balance weight is in a secured position within the slot; or(b) move the at least one balance weight towards the bottom surface sothat the shoulder surfaces do not engage the side walls at the balanceweight engaging section such that the at least one balance weight is ina unsecured position within the slot.
 22. The method of claim 21 whichcomprises the further step of associating with the balance weightsecuring member a locking member that prevents the balance weightsecuring member from being disassociated from the at least one balanceweight.
 23. The method of claim 21 wherein at least two balance weightsare inserted into the slot.
 24. The method of claim 23 wherein a pair ofbalance weights are inserted into the slot.
 25. The method of claim 23wherein the slot is formed in the balance weight retention member alongthe entire circumferential periphery thereof and wherein the opening ofthe slot has a substantially uniform width along the entirecircumferential periphery.
 26. The method of claim 25 which comprisesthe further step of moving the inserted balance weights in the slotuntil positioned approximately equally spaced from each other.
 27. Themethod of claim 21 wherein the rotary turbine component is a rotorpositioned within a turbine engine section having a radially extendingaccess pathway for accessing the balance assembly.
 28. The method ofclaim 27 for subsequent balancing of the rotor after insertion of the atleast one balance weight and positioning thereof at a first positionwithin the slot, and after the rotor is operated such that balancingthereof is needed, the method comprising the further steps of: (4)rotating the rotor such that the at least one balance weight isaccessible through the access pathway; and (5) moving the at least onebalance weight to a second position within the slot to achievesubsequent balancing of the rotor.
 29. The method of claim 27 whereinthe at least one balance weight is inserted within the slot before theretention member is secured to the rotor.
 30. A turbine engine sectionhaving a balance assembly for a rotary turbine component positioned inthe turbine section and a radially extending access pathway foraccessing the balance assembly for adjusting the position of at leastone balance weight within a slot of a balance weight retention member inthe balance assembly, the balance assembly comprising: a. a generallyannular balance weight retention member having a circumferentialperiphery and a generally dovetail-shaped slot formed therein along theentire length thereof, the slot having: (1) a bottom surface; (2) anopening spaced from the bottom surface; and (3) a pair of spaced apartand opposed side walls connecting the bottom surface and the opening,the side walls sloping inwardly at a section of the slot between thebottom surface and the opening; b. at least one balance weight beingconfigured and sized to be movable within the slot and having a pair ofspaced apart shoulder surfaces sloping generally inwardly so as to becapable of engaging the side walls of the slot at the balance weightengaging section; c. a balance weight securing member associated withthe at least one balance weight that can be actuated to: (1) move the atleast one balance weight away from the bottom surface so that theshoulder surfaces engage the side walls at the balance weight engagingsection of the slot such that the at least one balance weight is in asecured position within the slot; or (2) move the at least one balanceweight towards the bottom surface so that the shoulder surfaces do notengage the side walls at the balance weight engaging section of the slotsuch that the at least one balance weight is in an unsecured positionwithin the slot.
 31. The turbine section of claim 30 wherein the slot isformed in the balance weight retention member along the entirecircumferential periphery thereof.
 32. The turbine section of claim 31wherein there are at least two balance weights.
 33. The turbine sectionof claim 32 wherein there are a pair of balance weights.
 34. The turbinesection of claim 30 wherein the balance weight securing member comprisesa bolt having a threaded shaft and wherein the at least one balanceweight has a threaded portion for receiving the threaded shaft thatextends from the top to the bottom of the at least one balance weight.35. The turbine section of claim 30 wherein the rotary turbine componentis a rotor positioned within the turbine section and wherein the atleast one balance weight is inserted within the slot before theretention member is secured to the rotor.
 36. The turbine section ofclaim 30 wherein the balance weight engaging section of the slot hasgenerally trapezoidal shape.